1. Field of the Invention
This invention relates generally to an integral fiber optic printhead and, more particularly, to a printhead comprising a single fiber optic faceplate substrate.
2. Description of the Prior Art
Light emitting diode arrays are well known in the art for recording an image on a photosensitive medium such as a photographic film or paper or, alternatively, a photocopying receptor such as a selenium drum or a zinc oxide paper. In order to achieve high resolution, a large number of light emitting diodes are arranged in a linear array and means are included for providing a relative movement between the linear array and the photosensitive medium so as to effect a scanning movement of the linear array over the surface of the photosensitive medium. Thus, the photosensitive medium may be exposed to provide a desired image one line at a time as the LED array is advanced relative to the photosensitive medium either continuously or in a stopping motion. Each LED in the linear array is used to expose a corresponding pixel in the photosensitive medium to a value determined by image defining electronic signal information. Since the light emitted from each LED rapidly diverges upon emission from the diode, an optical system is needed to transmit the light from the LED to the surface of the photosensitive medium without substantial divergence. One such proposed optical system for use in such a printhead comprises an array of graded index lenses made up of closely packed rows of optical fibers as disclosed in U.S. Pat. No. 4,447,126, entitled "Uniformly Intense Imaging by Close Packed Lens Array", by P. Heidrich et al., issued May 8, 1984. Another apparatus disclosed for mounting an imaging lens array formed of a plurality of gradient index optical fibers onto a printhead having a linear array of light emitting diodes is suggested by U.S. Pat. No. 4,715,682, entitled "Mount for Imaging Lens Array on Optical Printhead", by K. Koek et al., issued Dec. 29, 1987. Although arrays of gradient index optical fibers have been suggested for use as the imaging lens in such printheads, critical alignment and assembly problems still exist so as to effect the precise connection between the optical fiber array and the LED array. Not only must the LED arrays be precisely aligned to the optical fiber arrays but electrical connections must also be made from remotely stationed control circuits which modulate the current furnished to drive the LED's during exposure.
Therefore, it is a primary object of this invention to provide an integral printhead structure in which LED arrays and the driver circuits therefor can be mounted on a singular substrate.
It is a further object of this invention to provide an integral printhead structure in which light emitting diode arrays are more easily connected to a fiber optic lens array which can further act as a substrate to accommodate the mounting and connection of additional support circuitry.
Other objects of the invention will be in part obvious and will in part appear hereinafter. The invention accordingly comprises a structure and system possessing the construction, combination of elements and arrangement of parts which are exemplified in the following detailed disclosure.